The loss of NH2O from the N-hydroxyacetamide radical cation CH3C(O)NHOH+: An ion-catalysed rearrangement

A mechanistic analysis using the CBS-QB3 model chemistry shows that the molecular ions HA-1 rearrange into hydrogen-bridged radical cations [OCC(H2)H⋯N(H)OH]+ whose acetyl cation component then catalyses the transformation NHOH → NH2O prior to dissociation. The high barrier for the unassisted 1,2-H shift in the free radical, 43 kcal mol−1, is reduced to a mere 7 kcal mol−1 for the catalysed transformation which can be viewed as a quid-pro-quo reaction involving two proton transfers.